Improved adaptor

ABSTRACT

There is provided a system for mounting an operative element (17) to a downhole tubular (12), the downhole tubular (12) having a longitudinal axis, the system comprising a releasable mandrelless tubing mount (14) wherein the tubing mount (14) is configured to be located at an axial location on the tubular (12) and is adapted in use to be substantially immobile and to interact with an operative element (17) configured to perform a function downhole.

FIELD

The present invention relates to an adaptor tool particularly, but not exclusively, for downhole use in the oil and gas industry.

BACKGROUND

An oil or gas well typically relies on downhole tools to control inflow and outflow. These downhole tools will be designed to perform specific functions, such as, but not limited to, zonal isolation, flow control, sand control.

These downhole tools may be situated anywhere in the well and will be connected end-to-end with tubulars to create a working string that is placed into the required position in the well. It is beneficial to minimise the number of connections in a working string to minimise the number of potential failure points and to improve efficiencies of installing working strings.

Tubulars within a working string are only available in limited length ranges which may be greater than the accuracy required for placement of downhole tools. It is therefore common for additional short sections of tubular, commonly referred to as pup joints, to allow for correct positioning of the downhole tools in the working string relative to the wellbore.

A downhole tool, such as an anchor, consist of a mandrel, setting mechanism, slips mechanism and release mechanism. The mandrel creates a fixed point on the working string for load to act against.

The mandrel is typically a specially designed item consisting of features such as threads, shoulders, sealing surfaces. These mandrels will typically be specifically machined to the correct geometry from a specific type of material which is compatible with the working string.

Additionally, tools, such as an anchor, must be designed to connect to the working string, and perform as per the specification of the working string, they were originally intended for. A downhole tool designed for one working string may therefore not subsequently be suitable for another working string. It is not uncommon for a surplus of downhole tools to be available onsite to be used as a back-up, in case of failure during running of a working string, thus leading to a surplus of downhole equipment which may not be fit for purpose or adaptable to other work strings.

Additionally, downhole tools are typically designed to perform specific functions and cannot be easily modified, either during or post manufacture, to perform different or additional functions.

If conditions or requirements change post manufacture the downhole tools may not be fit for purpose and replacements may be required at extra time and cost.

SUMMARY

There is provided system for mounting an operative element to a downhole tubular, the downhole tubular having a longitudinal axis, the system comprising a releasable mandrelless tubing mount wherein the tubing mount is configured to be located at an axial location on the tubular and is adapted, in use, to be substantially immobile and to interact with an operative element configured to perform a function downhole.

The system may further comprise a second releasable mandrelless tubing mount.

The or each releasable mandrelless tubing mount may further comprise a mount housing, at least one slip, a load sub and a load retainer.

The system may further comprise an assembly device configured to engage the mount(s) to provide preloading and secure the mount(s) to the outer surface of the tubular.

The assembly device may comprise a push sub configured to abut the load sub(s) of the mount(s).

The assembly device may further comprise a cavity between a piston housing and a mount piston, wherein the cavity may be configured to receive pressurised fluid.

The piston housing may be configured to move in a first direction, and the mount piston and push sub may be configured to move in a second direction opposite to the first direction.

The assembly device may be further configured to abut and move the load sub of the mount in the second direction.

The piston housing may be configured to engage the mount housing and exert a pulling force on the mount housing to squeeze the at least one slip between the mount housing and the load sub.

The system may further comprise an operative element mounted in use to the tubing mount.

The system may further comprise an operative element mounted in use between the first and second tubing mounts.

The system may be configured such that, in use, the operative element is in fluid communication with a bore of the tubular.

The operative element may be configured to be movable in response to an axial force.

The operative element may comprise a fixed element portion, an axially movable portion and a transversely movable portion coupled between the fixed element portion and the axially movable portion.

The fixed element portion may include a shear element having a yield strength sufficient to allow the fixed element to be transversely displaced to an engaged configuration and to shear in response to an axial force applied to the tubular when in the engaged configuration, and allow the transverse portion to retract whereby the mandrelless tool can be retrieved.

According to another aspect of the invention, there is provided a system for mounting an operative element to a downhole tubular, the system comprising a mandrelless tubing mount wherein the tubing mount is configured to be located at an axial location on the tubular and is adapted in use to be substantially immobile and to interact with an operative element configured to perform a function downhole.

The system may further comprise a second mandrelless tubing mount, wherein the tubing mounts are configured to be located at and axially spaced on the tubular and adapted in use to be substantially immobile and to interact with an operative element configured to perform a function downhole.

The mounts may each comprise a mount housing, at least one slip, a load sub and a load retainer.

In a further aspect of the present invention there is provided a mandrelless tool for mounting on a tubular, the tubular having a bore, and a longitudinal axis, the tool comprising:

a first tubing mount for releasably locating at a first axial location on the tubular,

at least one operative element coupled to the first tubing mount, the/each operative element being configured to perform a function downhole.

In some embodiments there may be a plurality of tubing mounts.

In one embodiment, the tool may further comprise a second tubing mount, the/each operative element being disposed between the first tubing mount and the second tubing mount.

The/each operative element may be movable between a first position and a second position.

In moving from the first position to the second position the/each operative element may move away from the longitudinal axis.

The/each operative element may move radially away from the longitudinal axis.

In an alternative embodiment, the/each operative element may move parallel to the longitudinal axis.

The first position may be a non-engaged configuration in which the/each operative element is displaced from an object to be engaged and the second position may be an engaged configuration in which the/each operative element is engaged with the object to be engaged.

In some embodiments the object to be engaged may be a casing.

In other embodiments the object to be engaged may be bedrock or any surface which may be found in a downhole environment.

In some of these embodiments the/each operative element may be a seal.

The/each operative element may be a cup seal, an inflatable seal, swellable seal or a packer. Any suitable operative element may be used to perform a task in a downhole environment.

There may be a plurality of operative elements.

In other embodiments the first position may be a closed position in which a port or the like in the tool is closed and the second position may be an open position where the port or the like in the tool is open or vice versa.

In some of these embodiments, the operative element is a sleeve.

The operative element may be movable by fluid pressure.

The operative element may be in fluid communication with the tubular bore. Fluid may be supplied through the tubular bore to move the operative element.

The operative element may be movable in response to an axial force.

The axial force may be applied by the fluid pressure.

Preferably, the operative element comprises a fixed element portion, an axially movable portion and a transversely movable portion coupled between the fixed element portion and the axially movable portion.

Preferably, the fixed element portion includes a first tapered surface and the axially movable portion includes a second tapered surface, the transversely movable portion having tapered surfaces for engaging with the first and second tapered surfaces.

Advantageously, the tapered surfaces are conical.

Preferably, the transversely movable portion is provided by a plurality of slips.

The slips may be arranged parallel to the longitudinal axis of the tubular and arranged circumferentially around the tubular.

Conveniently, the plurality of slips are located in a slip housing.

Conveniently, resilient means are coupled between the slips and the slip housing for biasing the slips into a non-engaged configuration in the absence of the axial actuation force.

Preferably, the transversely movable portion is provided by a piston.

The piston may be axially movable in response to an actuation force created by fluid pressure applied through the aperture in the tubular.

Preferably, the fixed element portion includes a shear element having a yield strength sufficient to allow the fixed element to be transversely displaced to the engaged configuration and to shear in response to an axial force applied to the tubular when in the engaged configuration, and allow the slips to retract into the slip housing whereby the mandrelless tool can be retrieved.

Preferably, the first tubing mount comprises a tubing mount housing, a plurality of mount slips, a mount load sub and a tubing mount load retainer.

According to another aspect of the present invention there is provided a retrievable mandrelless anchor for mounting directly on a tubular, the tubular having a bore, a longitudinal axis and an aperture in the tubular, the anchor comprising:

a first tubing mount for location at a first location on the tubular;

an operative element disposed between and coupled to the first and second tubing mounts, the operative element being movable in response to an axial actuation force between a non-engaged position and an engaged position, the operative element comprising an axially movable portion, a fixed portion and a transversely movable portion coupled between the fixed portion and the axially movable portion, the operative element being in fluid communication with the tubular bore via the aperture;

wherein in response to an axial actuation force created by the fluid pressure, the axially movable portion engages the transversely movable portion to move in a direction transverse to the axis of the tubular to the engaged position.

Conveniently, the transversely movable portion includes biasing means to bias the transversely movable portion to the non-engaged configuration in the absence of the axial actuation force.

According to a further aspect of the present invention there is provided a method of assembling a mandrelless anchor on a tubular having an aperture for applying fluid pressure through the aperture to an assembled anchor on the tubular, the method comprising the steps of:

securing a first tubing mount on to said tubular at a first location; and

assembling a plurality of mandrelless anchor components from a component assembly on the tubular anchor, the plurality of components including an axially movable portion;

aligning the aperture with the axially movable portion.

The method may further comprise the step of securing a second tubing mount on the tubular at a location axially spaced from the first tubing mount to abut an end of the component assembly

Preferably, the first mount is secured to said tubular by preloading.

It will be understood that features shown as optional with respect to the first aspect may be equally applicable to any other aspect and not been repeated for brevity.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will become apparent from the following description when taken in combination with the accompanying drawings in which:—

FIGS. 1a, 1b each are longitudinal axial sections through upper and lower tubing mounts in accordance with an embodiment of the invention;

FIGS. 1a,1b are longitudinal axial sections through an assembled mandrelless anchor in the run-in configuration in accordance with an embodiment of the invention;

FIG. 2 as a cross-sectional view through an assembled preload device for preloading the mandrelless anchor of FIG. 1;

FIG. 3 is a view similar to FIG. 2 with the preloaded tool engaged to apply a load to the mandrelless anchor of FIG. 1;

FIG. 4a,b depicts a part assembled and an exploded view of the mandrelless anchor of FIGS. 1a,1b , to a smaller scale, to illustrate the layout of the components used in the assembly;

FIG. 5 is a view similar to FIG. 1 with the mandrelless anchor actuated to the set configuration;

FIG. 7 is a view similar to FIG. 1 with the mandrelless anchor actuated to the released configuration, and

FIG. 8 is a longitudinal diagrammatic and a sectional view of an anchor according to the embodiment of the invention used in a straddle with two swellable packers.

DETAILED DESCRIPTION OF THE DRAWINGS

Reference is first made to FIGS. 1a and 1b of the drawings. FIG. 1a depicts a mandrelless tool 10 attached to the outside of a downhole tubular 12. The mandrelless tool 10 may be any form of downhole tool which before now may have been run on a dedicated mandrel within the working string. The tool may be, for example, but not limited to, a packer, stabiliser, anchor or zonal isolation, flow control, sampling or measurement tool. The tool 10 is held between an upper tubing mount 14 and an axially spaced lower tubing mount 16. The upper and lower tubing mounts 14, 16 provide fixation against which the tool 10 may be operated, for example the tool 10 may expand and be forced (by the fixed mounts 14, 16) to expand outwardly to contact the wellbore or casing.

It will be appreciated that where above mentioned use of two fixed points is not required, for example when running a measurement tool or a sampling tool, a single fixed point may suffice in the form of a single mount 14 used to attach a tool to the outside of a tubular 12.

The main components of the upper tubing mount 14 and lower tubing mount 16 are shown in the exploded view in FIG. 1b , with the tool 10 hidden for clarity. The upper tubing mount 14 comprises an upper mount housing 56, upper mount slips 54, an upper mount load sub 52 and an upper mount load retainer 58. The lower tubing mount 16 comprises a lower mount housing 93, lower mount slips 96, a lower mount load sub 98 and a lower mount load retainer 94.

The described upper and/or lower tubing mounts 14, 16 may be separate and distinct components from the tool to be attached to the tubular 12, or may be assembled with the tool for dispatch to the wellsite, at least in that the tool may be manufactured with upper and/or lower tubing mounts thereon which may later be removed for assembly and fixing to the tubular in stages as will later be described. In this regard, it will be understood that the embodiments herein described use a mandrelless anchor as a exemplary tool.

Reference is now made to FIGS. 2a and 2b of the drawings which depict a longitudinal axial section through an assembled mandrelless anchor 10. This anchor is designed for 7.00″ pipe with an 8.00″/8.125″ OD for running inside 9⅝″ casing. The anchor 10 is mounted on a tubular 12 and has an upper tubing mount 14 and an axially spaced lower tubing mount 16. Disposed between the upper and lower tubing mounts 14,16 is an expandable operative element, generally indicated by reference numeral 17, shown in broken outline, which comprises, in general, a movable piston 20, a movable upper cone 22 coupled to zo the movable piston 20, a set of slips 24 circumferentially disposed around the tubular 12, a fixed lower cone 28, a fixed lower cone housing 30, a lower retainer ring 32 and a shear ring 34. The tubing mounts 14, 16 have other components as does the expandable element 17 and these will be later described in detail.

The tubular 12 has a through aperture 35 which provides a fluid connection between a bore 13 of the tubular 12 and one side of the movable piston 20.

The arrangement shown in FIGS. 2a and 2b depicts the anchor 10 in the run-in configuration with the slips 24 shown retracted to a non-engaged configuration. The slips 24 are housed within a slip housing or cage 26, and are retained in the run-in configuration by a set of springs (not shown in the interest of clarity). As will be later explained in detail, in order to actuate the slips 24 to an engaged configuration, fluid pressure in the bore 13 is increased and this creates a force on the piston 20 which moves the movable upper cone 22 in the direction of arrow A to engage the slips 24 and move the slips 24 transversely in a radially outward direction to the engaged configuration for the slips 24 to engage an external tubular such as casing.

Reference is made to FIG. 3 of the drawings which depicts an assembly device 37 which is used to secure the upper and lower tubing mounts 14,16 to the tubular 12 by preloading the tubing mounts 14,16, as will be later described. The assembly device 37 consists of a piston housing 38,39, which surrounds a mount piston 40, with O-ring seals 44,46 being located between the piston housing 38 and the mount piston 40. An end 47 of the mount piston 40 abuts a push sub 48. The mount piston 40 also carries a piston nut 42 and the piston housing 39 carries a snap ring 50.

FIG. 4 of the drawings depicts the assembly device 37 shown in FIG. 3 mounted on the tubular 12 and engaging with the upper mount 14 so as to preload the upper mount 14 and secure it to the outer surface of the tubular 12 as will now be described. The upper mount 14 consists of three parts; a load sub 52, slips 54 and a mount housing 56. When the assembly device 37 is mounted on the tubular 12 shown in FIG. 4 an end 48 a of push sub 48 abuts the load sub 52. A cavity 57 between the piston housing 38 and mount piston 40 receives pressurised fluid which causes differential forces to act on the piston housing 38 and the mount piston 40. These differential forces cause the piston housing 38,39 to move in the direction of arrow A whereas the mount piston 40, the push sub 48 and the load sub 52 are moved in the opposite direction of arrow B. The piston housing 39 engages with mount housing 56 via the snap ring 50 and exerts a pulling force on the mount housing 56 to move the housing 56 in the direction of arrow A. As a result the slips 54 are squeezed between the housing 56 and the load sub 52 so that the serrated face 55 of the slips 54 bites into and engages with the outer surface of the tubular 12 thus securing the upper mount 14 to the tubular 12. An upper mount load retainer 58 butts out on the load sub 52. The assembly device 37 then has the pre-load released and is removed. This causes the pre-load to be transferred to the upper anchor load retainer 58 which locks the load into the slips 54.

Reference is now made to FIGS. 5a, 5b and 5c of the drawings which depict an exploded and itemised view of the components used in the build assembly of a mandrelless anchor 10 on the tubular 12. The assembly is made up from left to right in FIG. 5a , then in FIG. 5b and finally in FIG. 5c . Some items or components are not shown in the drawings in the interest of clarity. These are mainly screws used to stop items backing off or shearing.

The build steps are as follows:—

1. One or more holes 35 are drilled into the tubular 12 at a suitable location to allow for the make-up of the entire assembly.

2. The upper mount housing 56, slips 54, load sub 52 and upper mount load retainer 58 are made up as a sub assembly and slid over the tubular 12. These items are spaced out relative to the holes 35 drilled in step 1.

3. The assembly tool (not shown) is made up to the sub assembly (step 2) and a pre-load is applied through the load sub 52 and into the slips 54. As described above the assembly tool 37 locates and simultaneously pulls on the upper mount load retainer 58 using the groove 58 a shown in the outside diameter. This causes the load sub 52 to move axially to the left which in turn causes the slips 54 to move radially into the tubular 12.

4. As described above with reference to FIG. 4 the upper mount load retainer 58 is made up hand tight so that it butts out on the load sub 52. The assembly tool then has the pre-load released and is removed. This causes the pre-load to be transferred to the upper mount load retainer 58 which locks the pre-load into the slips 54 creating an upper mount point on the tubular 12 from which to build the rest of the assembly.

5. Next a seal shim 64, a tubing seal 66 and tubing seal retainers 68 a,b are made up onto the tubular 12 and inside the upper mount load retainer 58.

6. A piston body 70 is made up to the upper mount load retainer 58. This compresses the tubing seal 66 creating a seal between the piston body 70 and the tubular 12,

7. A piston housing 76 is made up onto the piston body 70 using o-rings and back-ups 81,83.

8. Tubing seal retainers 78 a,b and a tubing seal 77 are made up into the space between the piston body 70 and the tubular 12.

9. An upper retainer 80 is made up to the piston body 70. This compresses the tubing seal 76 creating a seal between the piston body 70 and the tubular 12. There are now seals at either side of the hole 35 in the tubular 12. Pressure is directed from inside the tubular 12 between these seals, through the hole 35 in the piston body 70 and between the o-ring and back-ups 81,83. The differential area creates a force which moves the piston housing 76 to the right which in turn will move the upper cone 22 which in turn sets the slips 24.

10. An upper body lock ring 84 and the upper cone 22 are made up to the upper retainer 80. The upper body lock ring 84 is split to act like a snap ring. It is expanded by accessing it through a slotted window 85 a in the OD of the upper cone 22. This allows the upper body lock ring 84 to be expanded and to pass over the threads on the upper retainer 80.

It will be understood that, where possible, parts are made up as sub-assemblies before being inserted onto the tubular 12. This may be done offline minimising the overall build time. For example, instead of making each part up one by one the next stage would be:

11. The slips 24 are inserted into the slip housing 26 and secured to the lower cone 28 using brass shear screws (not shown). A lower body lock ring 86 is pre-installed into the fixed lower cone 28. The lower retainer ring 32 is inserted under the lower body lock ring 86 which is expanded via a slotted window 85 a in the OD of the lower cone 28. A shear housing 88 and a shearing ring 90 are made up to the sub assembly. The shear ring 34 is split to act like a snap ring. It is expanded through a slotted window (not shown) in the OD of the shear housing 88 in order to locate it into a groove 92 on the lower retainer 32.

12. The sub assembly in step 11 can be made up onto the tubular 12 and is held in placed with brass shear screws which go through the slips and the moveable upper cone 22.

13. A lower mount housing 93 is made up onto the lower retainer ring 32.

14. The slips 96 are inserted into the lower mount housing 93 and are held in place with a cage or other suitable method (screws for example).

15. A lower mount load sub 98 is inserted into the lower mount housing 93 and a lower mount load retainer 94 is made up hand tight.

16. The assembly tool 37 is attached, pre-load applied as described above and the assembly tool removed in the same manner described in steps 3 & 4.

It will be understood that the assembly methodology allows for some axial adjustment to avoid issues with space out or movement of the lower mount. The space out from the fixed lower cone 28 onto the shear housing 88 and onto the shear ring 34 is arranged to avoid play because it is what takes the load off the slips when they are set. The upper body lock ring 84 also locks in the load.

The shear ring mechanism may be replaced for another mechanism where the tubing is punch or cut and this then causes the lower cone to release. zo These are all standard packer mechanisms.

Operation of the mandrelless anchor 10 as described above will now be described with reference to FIGS. 6a,b and 7 a,b of the drawings.

FIGS. 6a,b depict the mandrelless anchor 10 in a Set configuration, that is, after it has been run to the desired depth and then deployed by increasing pressure in the bore 13 which acts through hole 35 and generates a force which acts on the movable piston 20 forcing the moveable piston 20 and moveable upper cone 22 in the direction of arrow A. As the lower cone 28 is fixed, the piston force overcomes the restraining force of the slip springs and the slips 24 are forced radially outwards as shown to grip a surrounding tubular structure such as a casing.

FIGS. 7a,b depict the mandrelless anchor 10 in a Release configuration where the tool can be retrieved from the well. To move to this configuration from the Set configuration an upward pull is made on the tubular 12 while in the Set configuration, that is engaged and gripping the casing. The upper cone 22 abuts a sleeve (not shown) which prevents it from travelling any further towards the fixed lower cone 28. In response to an upward pull the shear housing 88 has travelled down towards mount load retainer 94 and in the process has sheared the shear ring 34. The top part of the shear ring 34 is detached and sits in groove 88 a. When this happens the lower cone 28 has also moved down and the force on the springs retracts the slips 24 inside the slip housing 26, as in the Run-in configuration. This means that the mandrelless anchor 10 and any associated tools can be retrieved from the well, the tool serviced and the shear ring 34 replaced, the tool reassembled as described above and made ready for further use.

Reference is now made to FIG. 8 of the drawings which shows an application of a mandrelless anchor 10 according to an embodiment of the invention where a leak in casing 100 resulting in water ingress from formation 102 needs to be sealed off. The anchor 10 is being used to anchor a swellable packer 99 to a tubular 12. A further swellable packer 101 is anchored to the tubular 12 by a second mandrelless anchor (not shown). The two swellable packers 99,101 straddle the casing leak 103 thereby containing the leak 103.

As well as being mounted to the tubular 12, the mandrelless anchor 10 is further secured casing 100 by slips 24 as previously discussed.

Various modifications may be made to the embodiment hereinbefore described departing from the scope of the invention. For example, the pipe size may be varied as follows for different pipe diameters : a 3½″ Tubing—7.00″ Casing—Approximately a 5.750″ OD 4½″ Tubing—7.00″ to 9⅝″ Casing—From 5.750″ to 8.125″ OD 5½″ Tubing—7⅝″ to 9⅝″ Casing—From 6.750″ to 8.125″ OD 9⅝″ Tubing—10¾″ to 13-38″ Casing—9.250″ OD to 12.250″ OD. It will be understood that suitably sized assembly tools will be used for different diameter pipes. The conical surfaces may be replaced by any other suitable tapered surface which can achieve the same effect to displace the slips when moving between the run-in and set configurations. Any suitable number of ports may be made in the tubular to provide fluid communication between the tubular and the piston. The piston may be any suitable shape. The shear ring may be replaced by any other suitable shear ring structure such as shear pins. The anchor may be used with any other downhole tools requiring anchoring such as cup seals, screens, valves, gauges, velocity string, liners, straddles, plugs.

An advantage of the invention is that it is made up onto oilfields tubulars, which have a standardised outsize diameter, and not a specifically designed mandrel, increasing the number of applications it can be applied to. Other advantages are that the design permits; flexibility to allow assembly on site or off-site; integration onto other tools which utilise tubulars, such as swellable packers; reconfiguration onto different tubulars, or tools, of the same outside diameter; reconfiguration to different tools requiring anchoring; reconfiguration into different embodiments of the design; 

1. A system for mounting an operative element to a downhole tubular, the downhole tubular having a longitudinal axis, the system comprising a releasable mandrelless tubing mount wherein the tubing mount is configured to be located at an axial location on the tubular and is adapted, in use, to be substantially immobile and to interact with an operative element configured to perform a function downhole.
 2. The system of claim 1 further comprising a second releasable mandrelless tubing mount.
 3. The system of claim 1 wherein the or each releasable mandrelless tubing mount further comprises a mount housing, at least one slip, a load sub and a load retainer.
 4. The system of claim 1, further comprising an assembly device configured to engage the mount(s) to provide preloading and secure the mount(s) to the outer surface of the tubular.
 5. The system of claim 4, wherein the or each releasable mandrelless tubing mount further comprises a mount housing, at least one slip, a load sub and a load retainer and the assembly device comprises a push sub configured to abut the load sub(s) of the mount(s).
 6. The system of claim 5, wherein the assembly device further comprises a cavity between a piston housing and a mount piston, wherein the cavity is configured to receive pressurised fluid.
 7. The system of claim 6, wherein the piston housing is configured to move in a first direction, and the mount piston and push sub are configured to move in a second direction opposite to the first direction.
 8. The system of claim 7, wherein the assembly device is further configured to abut and move the load sub of the mount in the second direction.
 9. The system of claim 8, wherein the piston housing is configured to engage the mount housing and exert a pulling force on the mount housing to squeeze the at least one slip between the mount housing and the load sub.
 10. The system of claim 1, further comprising an operative element mounted in use to the tubing mount.
 11. The system of claim 2, further comprising an operative element mounted in use between the first and second tubing mounts.
 12. The system of claim 10, configured such that, in use, the operative element is in fluid communication with a bore of the tubular.
 13. The system of claim 10, wherein the operative element is movable in response to an axial force.
 14. The system of claim 10, wherein the operative element comprises a fixed element portion, an axially movable portion and a transversely movable portion coupled between the fixed element portion and the axially movable portion.
 15. The system of claim 14, wherein the fixed element portion includes a shear element having a yield strength sufficient to allow the fixed element to be transversely displaced to an engaged configuration and to shear in response to an axial force applied to the tubular when in the engaged configuration, and allow the transverse portion to retract whereby the mandrelless tool can be retrieved.
 16. A system for mounting an operative element to a downhole tubular, the system comprising a mandrelless tubing mount wherein the tubing mount is configured to be located at an axial location on the tubular and is adapted in use to be substantially immobile and to interact with an operative element configured to perform a function downhole.
 17. The system of claim 16, further comprising a second mandrelless tubing mount, wherein the tubing mounts are configured to be located at and axially spaced on the tubular and adapted in use to be substantially immobile and to interact with an operative element configured to perform a function downhole.
 18. The system of claim 16, wherein the or each mount comprises a mount housing, at least one slip, a load sub and a load retainer.
 19. A mandrelless tool for mounting on a tubular, the tubular having a longitudinal axis, the tool comprising: a first tubing mount for releasably locating at a first axial location on the tubular, at least one operative element coupled to the first tubing mount, the/each operative element being configured to perform a function downhole.
 20. The tool of claim 19, further comprising a second tubing mount for locating axially spaced from the first tubing mount, the second tubing mount coupled to the operative element. 